1. Field of the Invention
The present invention relates to a substrate connector assembly for connecting one circuit substrate which includes wiring patterns spaced from each other by a required creepage distance for providing an isolation between the wiring patterns, with another circuit substrate having wiring patterns spaced from each other by a required creepage distance and to a computer system which includes such a substrate connector assembly.
2. Description of Related Art
An analog public telephone line is used as a communication path for communicating information between two computers, and a modem is mounted within the computer which performs a bidirectional conversion from the analog signal to the digital signal and from the digital signal to the analog signal. A modem card is a subsystem of the computer, and various semiconductor chips, devices and wiring patterns for interconnecting them are mounted on the modem card. In a computer which includes the modem card, the modem card is connected to a connector on the mother board to stack the modem card on the mother board. A portion of the wiring patterns of the modem card are connected to a modular jack attached to the mother board, and the modular jack is connected to the public telephone line.
Since the public telephone line can transfer a lightning surge voltage, an insulating transformer for preventing the surge voltage from being transmitted to the circuit in the modem card is mounted on the modem card. To protect the wiring within the computer (hereinafter xe2x80x9csecondary wiringxe2x80x9d) from the surge voltage on the wiring between the modular jack and the insulating transformer on the modem card (hereinafter xe2x80x9cprimary wiringxe2x80x9d), which is transmitted from the public telephone line, it is necessary to maintain a predetermined dielectric strength between the primary wiring and the secondary wiring. As one method for maintaining the required dielectric strength, a cable is used as the primary wiring. In the case that both the primary wiring and secondary wiring are formed on the mother board or the modem card, it is necessary to provide a sufficient creepage distance between the primary wiring and the secondary wiring. The creepage distance is known as the shortest distance between two conductors measured along a surface of the insulator on which the two conductors are formed.
If the wiring patterns of the mother board are used as the primary wiring, and the connector is used to connect the modem card to the mother board, it is necessary to maintain a sufficient creepage distance between the primary wiring and the secondary wiring on the mother board and to maintain a sufficient creepage distance between contacts of the connector for the primary wiring patterns and the contacts of the connector for the secondary wiring patterns. Since a pitch between the contacts of the connector used in the modem card is too short to provide a sufficient creepage distance, the primary wiring cannot be connected to the secondary wiring through such a standard type connector. To solve the problem without using the connector, the primary wiring formed as the wiring patterns of the modem card are directly connected to the modular jack by the cable, and the connector is merely used to connect the secondary wiring patterns on the modem card and the secondary wiring patterns on the mother board. In this case, an extra step is required to connect the cable between the modem card and the modular jack after the connection of the modem card to the connector on the mother board, so that the free disconnection of the modem card from the mother board is limited after the connection of the cable, and it is difficult to make a space for the cable connection in a small type electronic apparatus, such as a notebook computer.
In the case that, without using the cable, one end of the primary wiring patterns on the mother board are connected to the modular jack, and the other end of the primary wiring patterns are connected to the primary wiring patterns formed on the modem card through the connector, some contacts of the connector between the contacts used for the primary wiring and the contacts used for the secondary wiring are removed to provide the required sufficient creepage distance between the primary wiring and the secondary wiring on the connector. In this case, the problem arises in that the extra step for removing the unused contacts is required, and a rate of usage of the connector is decreased by the number of removed contacts.
In some cases, a key notch is formed on the modem card to prevent a misconnection of the modem card into the connector, and a key for engaging into the key notch is formed in the connector.
Accordingly, one object of the present invention is to provide a substrate connector assembly which includes a circuit substrate formed with wiring patterns which should be separated from each other by the creepage distance to provide a sufficient isolation, and a connector connected to the wiring patterns. Another object of the present invention is to provide a substrate connector assembly using a connector which provides the required creepage distance to provide a sufficient isolation between the contacts used for the primary wirings and the contacts used for the secondary wirings by utilizing a mechanism for preventing the misconnection of the connector.
Another object of the present invention is to provide a computer system using such a substrate connector assembly.
The present invention is directed to a substrate connector assembly which includes a first circuit substrate, a second circuit substrate and a connector mounted on the first circuit substrate for connecting wiring patterns formed on the first circuit substrate with wiring patterns formed on the second circuit substrate. The circuit patterns formed on the first circuit substrate include first wiring patterns capable of being connected to external wiring and second wiring patterns apart from the first wiring patterns by a predetermined creepage distance. The external wiring means the wiring that would be subject to a surge voltage from an external atmosphere, and hence which should be separated from the second wiring patterns by a predetermined creepage distance to maintain a required dielectric strength. An example of the external wiring is the public telephone line.
Further, the connector includes a contact array of a plurality of contacts and a key which is formed at a position for separating the plurality of contacts of the contact array into a first contact group and a second contact group for (1) preventing a misconnection of the second circuit substrate and (2) separating the first contact group from the second contact group by the predetermined creepage distance. The first contact group is connected to the first wiring patterns and the second contact group is connected to the second wiring patterns. The key can have a structure which is engaged with the key notch formed on the second circuit substrate to prevent the misconnection of the second circuit substrate, and formed at a position for separating the contact array.
Any specific structure of the key is not required in the present invention if the above function is performed. In the present invention, the key can perform its original function, and the decrease of the number of the contacts is not required to form the key in the present invention. In addition, the key of the present invention provides the required creepage distance between the first contact group and the second contact group. The position of the key can be determined in accordance with the number of contacts included in the first contact group.
Another embodiment of the present invention is directed to a computer system which includes a mother board, a connector mounted on the mother board and a circuit substrate connected to the connector. The mother board includes wiring patterns capable of being connected to external wiring and internal wiring patterns for the computer. The wiring patterns capable of being connected to the external wiring, such as the public telephone line, are separated from the internal wiring patterns by the creepage distance to maintain the required dielectric strength.
Further, the connector includes a contact array of a plurality of contacts, and a key which is formed at a position for separating the plurality of contacts of the contact array into a first contact group and a second contact group for (1) preventing a misconnection of the circuit substrate and (2) separating the first contact group from the second contact group by a predetermined creepage distance. The first contact group is connected to the wiring patterns capable of being connected to the external circuit and the second contact group is connected to the internal wiring patterns.
Further, the circuit substrate includes a pad array of a plurality of pads, each of which is connected to each of the contacts of the contact array and a key notch capable of being engaged with the key of the connector, which is formed at a position for separating the plurality of pads of the pad array into a first pad group and a second pad group. The circuit substrate includes the modem card.